"It's pretty much all the answers in terms of what you saw at Lake Silencio and in [series premiere] 'The Impossible Astronaut'," he explained. "We also truly find out about River Song (Alex Kingston) - who she is to the Doctor.

"There have been a whole lot of hints about a good man that she kills, and the reason why she's in prison. She certainly seems to behave like a lover or a wife to him, and this is where we say what that's all about."

Moffat admitted that he is looking forward to unravelling many of Doctor Who's recent mysteries.

"We've always talked about our plot arcs on Doctor Who, but, as you know, in the past they've been very slight," he said. "This has been a real ongoing story and it's nice to think everyone's now going to get answers to all their questions. Well, all except one, because that's the way I am!"